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The BumpMap Method

The second method, Deformation->BumpMap in the Model module, uses a more sophisticated and challenging technique to determine the height of each polygon in a mesh.

To start, you paint a 2D Image map, using the Softimage Paint program, Adobe Photoshop, or a similar image tool. The file should be a color image, where darker tones represent lower areas of geometry and lighter tones represent higher areas (see Figure 7.53). By painting a pattern of changing color values, you can precisely control the topography that is constructed.

Figure 7.53 A good starting image, with different hues indicating changes in topography.

The BumpMap tool can use changes in hue between the red, green, and blue channels to change the topography generated, as well as changes in the alpha channel. So feel free to paint different things in the R, G, B, and A channels to make a more complex landscape.

Convert the image to a Softimage .pic file if you use a separate tool, or just save it if you use the Paint program within Softimage 3D.

Next create a starting mesh object. The target mesh object should have enough detail to deform cleanly into the terrain shape, and can be either a polygon mesh, or a patch, including NURBS.

TIP:

The more detail the starting mesh has, the better looking the results will be. Particularly nice landscapes can be made by creating a Cubic NURBS grid with 15 cells in U and V, and moving groups of points manually to set the major features of the landscape before applying the BumpMap effect to fill in minor detail (see Figure 7.54).

Figure 7.54 A good starting mesh, with points raised to create major landmarks.

Invoke the Deformation->BumpMap command and set the parameters as you wish in the dialog box (see Figure 7.55).

Figure 7.55 The BumpMap dialog box.

Start by directing the tool to the picture file you want to use with the Browser button. Then pick the projection plane for the image to be mapped onto the surface. If the mesh is in the default XZ plane, visible from the top in the Top view window, use the ZX projection. The UV projection doesn't seem to work, so avoid it.

Figure 7.56 A greyscale displacement map painted to create an island for the Cyan CD-ROM game Riven. Printed courtesy of Cyan Inc. Copyright 1997.

The Height of Bumps control sets the overall amount of deformation applied by the effect in Softimage units. The contribution to that amount for each channel of the image (red, green, blue, and alpha) can be adjusted by setting the Channel factors from 0.0 to 1.0, where 0.0 is no influence at all and 1.0 is all the influence possible for that channel. (Setting the numbers higher than 1 has no effect.)

The Filter Type determines which filter is applied to smooth the map between vertices that fall between pixels, and Gaussian should yield more accurate results.

Figure 7.57 The island displacement map with the map of the island superimposed on it showing features. Printed courtesy of Cyan Inc. Copyright 1997.

You can choose to deform all the vertices on the mesh or only the tagged ones, and the vertices can be moved in a positive Y direction, or along the average of the neighboring normals. While moving along the normals yields more accurate and interesting results if you deform the surface manually before applying the effect, you will need less main bump height.

Click the Ok button to close the BumpMap dialog, and then pick the mesh to complete the effect (see Figure 7.54).

 

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